The present invention relates to a method for controlling an engine.
Current thermal enrichment delay/target algorithms delay enrichment without adequately ensuring that histogram-based catalyst and engine component temperature targets are met. It may be desirable to control temperatures based on the percentage of the component(s) life that it has spent above specific target temperatures.
It is an object of the present invention to provide a method of delaying temperature-based enrichment in order to maximize fuel economy and minimize emissions while still protecting engine components and emissions system within prescribed limits. The method according to the present invention provides temperature control delays based on target temperature. Once enrichment has been triggered, enrichment is continued to ensure the temperature of the component is below its target for a calculated time based on a specified percentage of time that the component is allowed to exceed it""s specified temperature, thereby ensuring that the temperature of the component has not exceeded its target temperature for more than a certain percentage of its life.